Thanks for the replies.
Don't think it's water, but could be ... maybe...
Water care is Ozone + HS ion, coupled with Spa Shock every use (virtually every night) Chlorine added twice a week, or after heavy use (4 adults) Water changed minimum every 6 weeks. (We use the tub a lot. Neighbors use tub a lot with us
) Water strip tested every couple days, and I do a complete test every 2 weeks or so...
Filters hosed out @ water change, and dishwasher cleaned every 3rd water change
Having said all that, I THINK I may have found the problem. Unzipped the cover, and bottom of plastic wrapped insulate was slimy/moldey took insulate out, and wiped down cover and insulate with bleach mixture.
Have not heard of this problem before, Is there anything that can be done preventitive?
Will report back tonight after tub reaches op temp, and see if smell returns...